An image forming apparatus such as a composite machine has at least two functions of a printer, a copier, or a fax machine. Toner is consumed when the image forming apparatus is used; thus, the toner needs to be successively replenished into a developing unit according to the amount of consumption. The toner is typically replenished into the developing unit from a toner container such as a toner cartridge or a toner bottle. When the toner container is empty, it is replaced with a new one.
There is known a cylindrical toner bottle for replenishing toner into the developing unit of the conventional image forming apparatus, such as that disclosed in Japanese Patent Application Laid Open No. 2000-338758 (hereinafter referred to as “first document”).
In the first document, the toner bottle is set in the body of the image forming apparatus (hereinafter, “apparatus body”) as follows.
First, a user pulls out a holding stand of a toner replenishing unit of the apparatus body, and takes out the empty bottle existing on the holding stand. The user then sets a new toner bottle sideways in the holding stand. The user pushes the holding stand with the new toner bottle into the back of the toner replenishing unit. Accordingly, a convex part provided on the bottom of the toner bottle engages with a joint part at the back of the toner replenishing unit. This fixes the position of the toner bottle in the toner replenishing unit.
Spiral protrusions are provided on the inner circumferential surface of the toner bottle. Thus, when the joint part is rotatably driven and the toner bottle is rotated, toner contained in the toner bottle is discharged from an opening. The toner discharged from the toner bottle is replenished to the developing unit.
The toner bottle constructed as above is relatively low-cost in that fewer components are used as compared to a toner container with a conveying member such as an agitator inside. Moreover, the above toner bottle is useful for recycling purposes, because it has a higher level of mechanical strength as compared to a bag-shaped toner container.
Because a user exchanges the toner container, the toner container should be easy to exchange, and toner scattering should be prevented so as not to soil hands and clothes of the user. Moreover, toner density becomes uneven if a stable amount of toner is not constantly discharged from the toner container and replenished into the developing unit. This can cause deterioration in image quality, such as blurring or uneven colors. Therefore, a stable amount of toner needs to be discharged from the toner container to the toner replenishing unit.
Various toner containers have been proposed and implemented to meet such demands. A well known example is a cylindrical toner bottle that has a spiral toner conveying part as disclosed in, for example, Japanese Patent Application Laid Open No. 2004-139031 (hereinafter referred to as “second document”).
On one end of this toner bottle is a mouth (opening) that has a smaller diameter than the spiral-shaped bottle body. This toner bottle is set in the apparatus body so that the bottle axis is substantially horizontal. Moreover, this type of toner bottle discharges toner from the mouth (opening) by being rotated. Furthermore, the toner bottle can be set from above the apparatus, and a grasping part (handle) is provided on the toner bottle. Thus, a user can easily set the toner bottle only by using his fingers.
FIG. 20 is a diagram of the toner container with the grasping part (handle) and the spiral toner conveying part.
As shown in FIG. 20, a toner container 101 includes a cylindrical container body 102, a cylindrical discharge member (lid) 110 that is attached to a mouth (opening) 103 of the container body 102, and a grasping part (handle) 111 is provided on the discharge member (lid) 110. The container body 102 is connected to the discharge member (lid) 110 by engagement of a projecting part 104 along the outer circumference of the container body 102 near the mouth (opening) 103 with a claw part 112 formed on the discharge member (lid) 110. Accordingly, the discharge member (lid) 110 and the container body 102 can be rotated integrally. The projecting part 104 and the claw part 112 are to be engaged with a gap within a fit tolerance (about 0.01 mm to 0.2 mm) used in machine designing, so that the discharge member (lid) 110 and the container body 102 can be rotated. An elastic member 113 such as foamed polyurethane with a thickness of 3 mm is attached to the discharge member (lid) 110. Therefore, as the side surface of the mouth (opening) 103 of the container body 102 is pressed against the elastic member 113, toner is prevented from leaking from where the container body 102 and the discharge member (lid) 110 contact each other.
The container body 102 of the toner container 101 is rotatably driven by a gear 106. Accordingly, toner stored inside is conveyed towards the mouth (opening) 103 by force of a spiral toner conveying part 105, and the toner is discharged out of a replenishing opening (not shown) provided on the circumferential surface of the discharge member (lid) 110. To rotate the container body 102, a predetermined gap is provided in the cylindrical direction of the toner container 101 where the discharge member (lid) 110 overlaps with the container body  102 (in the example in FIG. 21, a 2 mm gap is provided in a radial direction). In other words, the toner container 101 is provided with a gap ΔL of substantially 2 mm in the radial direction where the discharge member (lid) 110 overlaps with the container body 102.
However, in the conventional technology disclosed in the first document, a user cannot clearly feel a mechanical click when attaching the toner bottle to the apparatus body. Thus, there is a possibility that the toner bottle is not set properly.
Specifically, when the user sets the toner bottle on the holding stand pulled out from the toner replenishing unit, the user cannot feel safe and sure that the toner bottle is set properly. Only after the user pushes the holding stand with the toner bottle into the toner replenishing unit, the user can feel safe and sure that the toner bottle is set properly.
This means that there is a possibility that the toner bottle is not set properly when the toner bottle is being set on the holding stand. If the holding stand is pushed into the toner replenishing unit with the toner bottle not properly set, components of the toner replenishing unit or the toner bottle can break. Moreover, if the toner bottle does not engage with the joint, toner might not be replenished properly.
The toner container with the grasping part (handle) and the spiral toner conveying part disclosed in the second document has the following problem. When a user sets the toner container 101 shown in FIGS. 20, 21 into the image forming apparatus, the user holds it with the grasping part (handle) 111 to hold the whole toner container. The grasping part (handle) 111 is located on the discharge member (lid) 110 at one end of the toner container 101, and there is the gap within a fit tolerance between the toner container 101 and the discharge member (lid) 110. Thus, the toner container 101 is only held at one end, and the container body 102 tilts downward. In other words, because of the weight of the container body 102 including the toner stored, the bottom side opposite to the discharge member (lid) 110 tilts downward. As a result, a rotational central axis C1 of the container body 102 deviates from a central axis C2 of the discharge member (lid) 110, as shown in FIG. 21. In this state, the container body 102 can loosen from the discharge member (lid) 110, and a gap can be formed in between. If the toner container 101 is attached to the apparatus body in such state, toner leaks out and scatters from the loose part or the gap, by a shock caused by the attachment. In some cases, the toner might be saved from leaking from the loose part. However, if the rotational central axis of the container body 102 is tilted when the toner container 101 is attached to the apparatus body, the gear 106 deviates from the rotational central axis. This creates a fluctuation and increases a rotational torque of driving the apparatus body.
The present invention is made in view of the above. An object of the present invention is to provide a powder container and an image forming apparatus with which a user can clearly feel a mechanical click when attaching the container to the body of the image forming apparatus. Moreover, the object of the present invention is to ensure that the powder container is set properly, so that the rotational central axis of the container body is prevented from deviating from the central axis of the discharge member (lid part), to prevent powder scattering and a torque increase, with a simple construction. In other words, the object of the present invention is to provide a powder container and an image forming apparatus, such that the powder container is surely attached to the body of the image forming apparatus.